Various forms of shading systems that control the transmission of light exist. They include conventional window treatments, such as curtain, draperies, blinds, louvers, and the like. These have the disadvantage that there is always some non-transparent foreign object near the windows that must be moved out of the way to allow light to transmit through.
To address this deficiency, “smart windows” have been developed, such as photochromic windows, thermotropic windows, thermochromic windows, polymer dispersed liquid crystal windows, suspended particle system windows, electrochromic windows, and gasochromic windows. A review of these types of windows are found in Background of the Invention section of United States Publication No. 2009/0296188. Although these smart windows provide certain improvements over conventional window treatment, they are extremely costly and/or difficult to fabricate or replace.
Various forms of displays that provides desired messages exist. They include static displays that cannot change once a message is imprinted, dynamic displays based on holography, dynamic displays that require electrical power (e.g., computer screens), and the like. However, such displays are limited (e.g., static) or expensive to operate and/or manufacture (e.g., holography and/or computer screens).